best thing to do is... as others have said... fresh install including all of your apps
then... to migrate the user(s) folders over from your old iMac to the new one... connect a firewire cable between the 2 machines... boot your old iMac holding down the "T" key... which will boot it into "target disk mode"
once booted.. a firewire icon should be bouncing around the screen of your old iMac... and a HDD icon appear on your new iMac
once that has occured... open migration assistant located in the applications folder > utilities folder and go from there... if you have setup all of your apps initially... there is no need to copy over the apps... just the user account(s) that you need
once done... you can disconnect the firewire cable... and be good to go
hope this helps
yukioMishima